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  <script>
    var arr = ['q', 'w', 'w', 'e', 'q', 'q', 'r']

    var newArr = []

    for(var i = 0; i < arr.length; i++) {
      //  当新数组 不包含 当前项 我们就进入添加新数组操作
      if( newArr.indexOf( arr[i] ) === -1 ) {
        newArr.push( arr[i] )
      }
    }

    console.log( newArr )

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